Parvovirus PCR

Parvovirus B19 is a virus that causes a common childhood illness, also called "fifth disease" or "erythema infectiosum." It is also known as “Slapped Cheek Disease” because of the typical rash that appears in some children. The virus is found in respiratory droplets during an infection and is easily transmitted to others through close physical contact (coughing or sneezing). In the United Kingdom, 60% of adults and 90% of the elderly have been infected with parvovirus B19 at some time in their lives, usually as children or young adults. The infection typically has an incubation period of several days to two to three weeks. It is often asymptomatic (no symptoms are apparent) but where symptoms occur, they are present for a short period of time.

For most people, parvovirus B19 infection is indistinguishable from other mild illnesses that develop and go away after a short period. Many who are infected have no symptoms or have mild flu-like symptoms such as tiredness, a slight fever, headache, or an upset stomach, and many may not know that they have had a parvovirus B19 infection. The majority of people do not have any significant symptoms or health problems and once the initial infection resolves, the person becomes immune to the infection and will not get it again.

Some children with the infection develop a characteristic and distinctive bright red "slapped-cheek" rash on both cheeks and a raised lacy rash on the chest and extremities. The rashes may come and go for several weeks, reappearing and/or getting worse with exposure to heat and sunlight and with stress. By the time the rash appears, the child is no longer considered infectious. Parvovirus is sometimes called fifth disease because it is the fifth of six common childhood illnesses that can cause rashes.

Less commonly, some adults become infected and may develop "gloves and socks syndrome" with painful swelling of joints and reddening of the hands and feet that typically ends abruptly at the wrists and ankles. This condition usually resolves within a few weeks.

Parvovirus can also be passed from a pregnant woman to her foetus and through blood and blood products. Sometimes, the infection can lead to more serious disease.

Parvovirus B19 can cause major health problems in three types of patients:

• People with iron deficiency anaemia or a condition that affects or shortens the life of red blood cells (RBCs), such as iron deficiency anaemia or thalassaemia, may develop severe acute anaemia during a parvovirus B19 infection. Parvovirus B19 targets cells in the bone marrow that become RBCs and disrupts the production of new RBCs, which may affect those with underlying blood disorders more severely.
• Women who are infected during pregnancy can pass the infection to their baby. Most foetuses will be fine, but a small proportion will develop severe anaemia and a few may have an inflammation and infection of the heart muscle (myocarditis). These conditions can cause heart failure in the foetus, miscarriage, hydrops fetalis - associated with fluid accumulation, and sometimes stillbirth. The greatest risk for foetal complications is during the first twenty weeks of pregnancy.
• In those with compromised immune systems, a parvovirus B19 infection may cause chronic anaemia and be challenging to resolve. This includes people with HIV/AIDS, those who have had organ or bone marrow transplants, and those undergoing chemotherapy treatment for cancer.

Parvovirus B19 testing is not typically used to screen the general population. It is usually requested to find out whether someone is, or has recently been, infected with parvovirus if they are at risk of complications. This enables the most appropriate treatment to be given to minimise the consequences of parvovirus B19 infection. It may also sometimes be necessary to find out whether someone has ever been exposed to parvovirus (for example if they are in a higher parvovirus B19 disease risk group and have recently been in contacted with a patient with parvovirus B19 symptoms). Testing involves either a measurement of parvovirus antibodies, immune proteins produced in response to parvovirus B19 exposure, or the detection of the genetic material of the virus itself (its DNA) during an active infection.

How is the sample collected for testing?

The sample required depends on whether testing is being done to look for the presence of antibody or to detect the virus itself and it also depends on the health of the patient. Antibody testing requires a blood sample, obtained by inserting a needle into a vein in the arm. Viral detection may be done on blood or more rarely on a sample of bone marrow collected through a bone marrow aspiration or biopsy.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.